Liquid crystals are an essential component of many types of optical displays. The usefulness of liquid crystals for application in this area is related to the strength and position of the polar groups in the liquid crystal molecule and the degree of dielectric anisotropy the liquid crystal exhibits (T. Inoi, Organofluorine Chemistry, Principles and Commercial Applications, Ch. 12, “Fluorinated Liquid Crystals”, Plenum Press, New York, R. E. Banks et al., eds., (1994), pp. 263-286). Accordingly, the literature shows that a number of liquid crystals used in active matrix displays have evolved into those containing highly polar head groups, quite notably perfluorinated ones such as CF3, (T. Inoi, ibid) which impart a dipole on the molecule in order to achieve an improved dielectric anisotropy and hence enhanced performance.
Kirsch et al in Liquid Crystals 1999, 26, 449 described the preparation of liquid crystal compositions bearing a fluorine atom and a geminal alkenyl substituent on a quaternary carbon of a cyclohexane derivative. These compounds possess negative dielectric anisotropy and formed nematic mesophases with low rotational viscosity making them suitable for use in thin film transistors with multi-domain vertical alignment. Reiffenrath and Lussem in US Published patent application SN 2002/0117650 filed 19 Jul. 2001 reported on compounds bearing a CF3— group and a geminal alkynyl group on a cyclohexane derivative. They suggested that these compounds are suitable for use in liquid crystalline media.